According to the many methods of operation involved in computer-aided embroidery machines prevailing on the market nowadays, the operators have to designate the patterns and set the embroidering conditions in advance. Quite often either the embroidering operation will exceed the embroidering range of the embroidery table such that the danger of machine bumping occurs, or the pattern contour embroidered will exceed the range of the embroidery frame. In both situations, the machine won't meet the required performance. However, if the operators adopt a relatively conservative way of setting the operating conditions in order to prevent the machine bumping from occurring, they cannot make the most of the embroidering space of the machine table, thereby imperceptibly reducing the available area used by the machine table, and greatly reducing its practical use.
On the other hand, as it was taught in the prior art, Japan's patent No. 63-105787 discloses a method to attain the embroidering testing function by use of a display device. The method disclosed therein is to show the actual embroidered pattern and the embroidery frame on the display device to allow the use to determine if the pattern is beyond the range of the embroidery frame. One of the shortcomings of this method is that the operator needs to have the geometric contour of the embroidery frame and its corresponding locations of the machine table, so as to be able to attain the embroidering result on the display device. The embroidery setup lead time can be greatly improved, and the chances of machine malfunction and damages can also be reduced greatly. Another prior art, Japan's patent No. 63-197488, discloses a method which requires the operator to examine only the relative locations between the needlebar and the embroidery frame during the course of embroidering testing without having to drop the needle but only have to move the frame. The shortcoming is that the user needs to perform the embroidering testing, stitch by stitch, to embroider the whole pattern beyond the frame. It is very time-consuming, and, therefore, is not practical. As for U.S. Pat. No. 5,072,680, it discloses a method to project, by installing a light source projector on the top of the embroidery frame, the range of the actual embroidering area, on the embroidery table to provide the operators with the information if the size of the pattern intended to embroider exceeds the range of the embroidery frame. However, the shortcoming of this method is that the user needs to add an additional hardware which would raise the machine cost accordingly.